Rivastigmine hydrogen tartrate is chemically known as (S)—N-Ethyl-N-methyl-3-[1-(dimethylamino) ethyl]-phenyl carbamate hydrogen-(2R, 3R)-tartrate (hereinafter referred to as “rivastigmine tartrate”) and has structural Formula I.

Rivastigmine hydrogen tartrate is administered for the inhibition of reversible cholinesterase and is marketed under the brand name EXELON™ as capsules containing 0.5, 3, 4.5 and 6 mg rivastigmine base equivalent.
U.S. Pat. No. 4,948,807 describes the compound N-ethyl, N-methyl-3-[1-(dimethylamino)ethyl]phenyl carbamate and its pharmacologically acceptable salts along with a pharmaceutical composition useful for treating anticholinesterase activity in humans.
U.S. Pat. No. 5,602,176 describes (S)—N-ethyl-3-[(1-dimethylamino)ethyl]-N-methyl-phenyl carbamate in free base or acid addition salt form as useful for its anticholinesterase activity.
International Application Publication No. WO 2004/037771 A1 and European Patent 193926 describe a process for the preparation of (S)-3-[1-(dimethylamino)-ethyl]-phenyl-N-ethyl-N-methyl carbamate by the reaction of optically active m-hydroxyphenylethyl dimethylamine with a carbamoylhalide
International application No. WO 2005/058804A1 describes a process for the preparation of rivastigmine by stereoselective reduction.
Consequently, it would be a contribution to the art to provide a process for the preparation of rivastigmine and its salts, which would be environment-friendly and suitable for commercial manufacturing.